Yep, I use Flurry. It's great. Add the jar and a few lines of code, and you get a ton of information about usage. You can also easily define custom events, so you know how many times users pressed button X, or how many times they died on level 3.

I tried using Google Analytics, but went back to Flurry after a few days...it was just better.

The one area they both suck at is error reporting. Flurry let's you do error reporting, but sends back so little information it's essentially useless. I ended up implementing my own remote error reporting.

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